Sea level rise threatens the Everglades and the whole of south Florida
Written by Tim
“The Everglades is the strangest National Park you’ll ever visit,” says Larry Perez the Park’s Science Communications Liaison Officer. More than a million visitors a year “endure hours of travel just to see grass”. Actually, what appears to be a sea of grass is a unique habitat where fauna from temperate North America live on vegetation found in the Caribbean. Sixty percent of the park is less than one metre above sea level so the glades are extremely vulnerable to sea level rise. “Centimetres of relief mean everything here,” said Perez and minute variations in elevation completely alter the local vegetation profile.
Cape Sable on the south western shore of the Everglades “is our canary in the coalmine” said Perez. “Whatever is destined to happen to other coastal Florida communities, is likely first to occur at Cape Sable.”
Along the Cape coastlines receded by between 150 and 300 metres between 1928 and 2005. And according to Harold Wanless, Professor of Geology at the University of Miami the 23cm rise in sea level since 1930 has destabilised all of Cape Sable’s coastal and wetland environments.
People have altered the hydrology of the south Florida landscape since the 1880s, digging canals to drain the marshland, connecting freshwater systems with ocean water and tides. They drained land for cultivation but this also allowed saltwater to flow up the canals into previously freshwater areas.
Untangling the relative impacts of sea level rise, human modifications and natural processes such as hurricanes, rainfall fluctuations and periodic frosts is complicated. But whatever the cause salt water is encroaching further and further inland leading to the degradation of the Everglades.
The U.S. Army Corps of Engineers and the South Florida Water Management District developed a plan “to save the Everglades” which includes plugging canals to prevent the intrusive flow of saltwater. However, if sea levels continue to rise this can at best be a temporary measure.
Professor Wanless thinks “Everglades restoration is probably worth doing” but that the longer term outlook is gloomy.
Perez agrees. If the IPCC’s 2007 sea level projection proves true, “the potential loss would be 50% of the freshwater ecosystem in the park”.
Floridians are not just losing a wilderness area and a unique habitat. Loss of the park’s mangrove strand will devastate the commercial and recreational fisheries of the Biscayne and Florida Bays. And what is happening in the glades is happening elsewhere. High tides on Miami Beach rush through the drains flooding the city’s streets with saltwater.